Field of the Invention
The present invention generally relates to a system for purging non-condensable gas from a refrigeration circuit, and a refrigeration circuit equipped with the purge system. More specifically, the present invention relates to system for purging non-condensable gas from a chiller circuit that uses a low pressure type refrigerant without requiring a separate dedicated compressor.
Background Information
A refrigeration circuit for a chiller system typically includes a purge system for removing non-condensable gases from the refrigerant circuit. Accumulation of non-condensable gases in the refrigeration circuit can degrade the operating efficiency of the chiller system. The purge system removes the accumulated non-condensable gases to prevent or suppress such a degradation of the operating efficiency.
A conventional purge system has a complete refrigeration circuit that includes a condenser, an expansion valve, a heat exchanger coil (evaporator coil), and a dedicated compressor (which is separate from the compressor of the main refrigeration circuit of the chiller system). The purge system also includes a purge tank that defines a condensing chamber and houses the heat exchanger coil of the purge system refrigeration circuit. The purge tank has an inlet for introducing refrigerant containing non-condensable gases from the main refrigeration circuit of the chiller system to the condensing chamber, an outlet for returning condensed refrigerant back to the main refrigeration circuit from the condensing chamber, and a purge outlet for purging accumulated non-condensable gases to the ambient atmosphere. A purge line communicating to the ambient atmosphere is connected to the purge outlet, and a pump-out compressor and a carbon filter or other device for removing residual refrigerant from purged gases are provided in the purge line. The purge line also includes valves for opening and closing different sections of the purge line.
Refrigerant containing non-condensable gases is introduced into the condensing chamber of the purge tank from the main refrigeration circuit and condensed by the evaporator coil. Liquid refrigerant collects in the bottom of the condensing chamber and the non-condensable gases accumulate in the condensing tank and remain in a gaseous state. Periodically, the non-condensable gases are purged from the condensing chamber by opening the valves of the purge line and operating the pump-out compressor to draw the non-condensable gas from the condensing chamber and pump the non-condensable gas out to the atmosphere. When the non-condensable gas is purged, residual refrigerant exiting the condensing chamber along with the non-condensable gas is captured by the carbon filter such that the refrigerant is not released to the atmosphere. FIG. 14 shows a schematic view of a conventional chiller system equipped with a conventional purge system. Also, Japanese Patent Application Publication No. 2010-531970 (which corresponds to International Patent Application Publication No. WO2009-114398) discloses a purge system installed in a chiller system that uses a low pressure refrigerant.